Apparatus for dispensing beverages

ABSTRACT

An apparatus for dispensing semi-frozen beverages containing water, a flavoring syrup and carbon dioxide in which the water and flavoring syrup are delivered under a pre-set substantially constant pressure through respective water and syrup flow restrictors to a mixed beverage delivery line so that the proportions of the water and syrup in the mixed beverage are controlled by the water and beverage flow restrictors. The apparatus includes mechanism for selectively passing water under the gas pressure in a reverse direction through the syrup flow restrictor to back flush and clean the same. The apparatus also includes mechanism for automatically controlling the flow of mixed beverage to the freezing chamber and the venting of gas from the freezing chamber to maintain the liquid in the chamber at a preselected level and pressure.

BACKGROUND OF THE INVENTION

Beverage dispensing apparatus have heretofore been made in which aflavoring syrup is separately stored and then mixed with water toproduce a beverage. It has heretofore been proposed to make a beveragedispensing device utilizing separate water and syrup metering orificesfor respectively metering the flow of water and syrup to a dispenser.However, the flavoring syrup concentrate frequently contains or formsgelatinous and or crystaline particles which tend to clog the syrupmetering orifice and markedly change the proportions of syrup and waterin the mixed beverage. In the prior dispensing apparatus of this type,it was necessary to disassemble the syrup metering orifice and syrupfilter in order to clean the same. The disassembly, cleaning andreassembling of the syrup orifices and filters was tedious and timeconsuming and such prior apparatus were objectionable either asrequiring too much operator time in order to maintain proper operationor as being inaccurate in metering if the operator failed to clean thesame as often as necessary. In order to overcome the above difficultiesencountered in orifice type metering devices, it has also been proposedto use a positive displacement type pump for positively pumping thewater and the syrup to the dispenser. While such devices are lesssusceptible to problems due to gelatinous or crystaline particles in thesyrup, they are more complex and hence more expensive to build anddifficult to service.

It has also been known to produce semi-frozen or slush type carbonatedbeverages by passing a carbonated beverage mix to a freezing chamberthat refrigerates and agitates the carbonated beverage to form asemi-frozen product. Some prior apparatus operate the freezing chamberat atmospheric pressure. However, the carbon dioxide tends to escapefrom the beverage at atmospheric pressure, particularly when allowed tostand for a substantial period of time, and the yield or overrun in suchapparatus is not as high or as uniform as is desirable. In order toachieve a higher and more uniform yield or overrun, it has also beenproposed to operate the freezing chamber at above atmospheric pressure.However, in such pressurized freezing chambers difficulties areencountered in accurately controlling the pressure and liquid level inthe freezing chambers.

SUMMARY OF THE INVENTION

The present invention generally relates to an apparatus for dispensingbeverages containing water, a flavoring syrup and food-grade gas. It isan object of this invention to provide an apparatus for dispensingbeverages having an improved system for proportioning the water andflavoring syrup and which is simple to operate and which willconsistently produce a beverage of preselected composition.

Another object of this invention is to provide an apparatus fordispensing beverages in which proportioning of the water and flavoringsyrup is effected by water and flavoring syrup flow restrictors and inwhich the syrup flow restrictor can be cleaned in place and in a veryshort time and without adverse affect on the beverage ingredients orbeverage mixture in the remainder of the dispenser.

A more particular object of this invention is to provide an apparatusfor dispensing beverages in accordance with the foregoing object inwhich the cleaning of the syrup orifice is effected by back flushing ofthe syrup orifice while in place in the system and utilizing water underthe gas pressure of the system.

Yet another object of this invention is to provide a beverage dispensingapparatus in which the relative proportions of syrup and water can bereadily adjusted and the adjusted mixture then sampled without drainingall or a substantial part of the beverage dispensing system.

The present invention also relates to an apparatus for dispensingsemi-frozen beverages containing a water or flavoring syrup and afood-grade gas.

It is another object of this invention to provide an apparatus fordispensing semi-frozen beverages having an improved arrangement fordelivering the beverage to a freezing chamber to produce a semi-frozenproduct therein.

Another object of this invention is to provide an apparatus fordispensing semi-frozen beverages in accordance with the foregoing objecthaving an improved arrangement for maintaining the liquid in thefreezing chamber at a preselected level and in a preselected pressurerange to provide a frozen beverage having more uniform composition; tominimize spurting during dispensing; and to prevent build-up ofexcessive pressure in the freezing chamber due to expansion of theproduct during freezing.

These, together with other objects and advantages of this invention willbe more readily understood by reference to the following detaileddescription when taken in connection with the accompanying drawingswherein:

FIG. 1 is a diagrammatic view of a beverage dispensing system embodyingthe present invention for preparing and dispensing a semi-frozenbeverage;

FIG. 2 is a schematic diagram of the electrical control system for thebeverage dispensing system of FIG. 1;

FIG. 3 is an end elevational view of an apparatus for proportioning thebeverage ingredients;

FIG. 4 is a sectional view taken on the plane 4--4 of FIG. 3;

FIG. 5 is a sectional view taken on the plane 5--5 of FIG. 3;

FIG. 6 is a fragmentary front elevational view of a machine fordispensing a semi-frozen beverage; and

FIG. 7 is a fragmentary schematic view illustrating a modification inthe electrical control apparatus of FIG. 2.

The principles of the present invention are particularly useful whenembodied in a beverage dispensing apparatus such as shown in thedrawings and designated generally by the numeral 10. The system ingeneral includes a water storage vessel 15, a syrup storage vessel 16,and a tank 17 containing a food-grade gas such as carbon dioxide. Thewater and flavoring syrup are delivered under gas pressure to aproportioning apparatus 19 to a freezing and dispensing cylinder 21. Thebeverage dispensing machines are frequently arranged to dispense two ormore beverages as shown in FIG. 6. However, the beverage dispensingsystem is substantially duplicated for each different beverage to bedispensed. Accordingly, only a single beverage dispensing system isdescribed herein.

The water supply vessel is preferably maintained filled to a preselectedlevel and, for this purpose, a water supply source such as aconventional municipal supply S is connected through a pressureregulator 23, a valve 24 and line 25, to a water inlet 26 that extendsinto the vessel 15. The water pressure regulator 15 is set to deliverwater to the water storage vessel under a pre-set pressure describedmore fully hereinafter and the valve 24 is operated by a level control31 in the vessel 15 between an open and closed position to maintain theliquid level Lw in the vessel 15 within a preselected range.

The water in the storage vessel 15 is preferably cooled to a preselectedtemperature by the evaporator coil 32 of the refrigeration system thatincludes a compressor 33, condenser 34 and refrigerant expansion valve35, and the refrigeration system is cycled on and off by a temperaturecontrol 126 to maintain the temperature in the storage vessel somewhatabove the freezing temperature of water, for example about 34° F. Thewater entering the water storage vessel is preferably pre-cooled by apre-cooled coil 37 in the water inlet line 25 and disposed around thevessel in heat exchange relation with the refrigerant evaporator coil32.

Gas from the gas storage tank 17 is supplied through an on-off valve 41,adjustable flow regulator 42 and line 43 to the gas inlet 44 of thewater storage vessel to maintain the water therein under a preselectedsubstantially constant gas pressure determined by the pressure regulator42. The gas is preferably carbon dioxide and the vessel 15 is preferablyconstructed as a conventional carbonator having means such as a gasdiffuser 46 in the vessel for increasing the water-gas interface andthereby enhance absorption of the gas by the water.

Water under the pressure of the gas in the vessel 15 is fed through awater delivery line 51 to the proportioning apparatus 19. The syrup inthe syrup storage vessel 16 is also maintained under substantially thesame preselected gas pressure and is fed through a syrup delivery line52 to the proportioner apparatus 19. As shown, gas under pressure fromthe water storage vessel 15 is supplied through a gas transfer line 53to the syrup storage vessel 16 to maintain the latter under the samepressure as the water in the storage vessel.

Water and syrup under substantially the same gas pressure are meteredand mixed in the proportioning apparatus 19 and the mixed beverageingredients are supplied through a mixed beverage delivery line 54having a delivery valve 55 therein for controlling flow through thedelivery line. The proportioner has a water inlet 51a connected to thewater delivery line and water from the water inlet passes through acheck valve 56 and water flow restrictor 57 to a mixing chamber 58 asshown in FIG. 4. The check valve 56 is conveniently in the form of aresilient lip sealing valve and the flow restrictor 57 is in the form ofa restricted passage in the body of the proportioner apparatus. Theproportioner has a mixed beverage outlet 59 that communicates with thechamber 58 and which is connected to the mixed beverage delivery line54. A syrup sensor 62, conveniently in the form of a float operatedswitch, is provided in the syrup delivery line 52 to sense when syrup ispresent or absent in the delivery line and the proportioner 19 has asyrup inlet 52a connected to the syrup delivery line 52. Theproportioner 19 also has a syrup flow restrictor 66 having its outlet66a connected to the mixing chamber 58 and an inlet 66b connected to theoutlet 67a of a syrup filter 67. The syrup filter has an inlet 67bconnected through a syrup control valve 68 to the syrup inlet. Asdiagrammatically shown in FIG. 1, the syrup control valve 68 is of athree-way type and is normally positioned as by a spring 69 in aposition passing syrup from the syrup inlet 52a to the inlet 67b of thesyrup filter 67 for flow through the syrup flow restrictor 66 to themixing chamber 58. At least one of the flow restrictors 57, 66 isadjustable and, in the preferred embodiment, the syrup flow restrictor66 is made adjustable to vary the relative proportions of the water andsyrup which will flow through the respective flow restrictors under thesame substantially constant preselected pressure to the syrup line, whenthe delivery valve 55 is open. As best shown in FIG. 4, the adjustableflow restrictor 66 is of the adjustable orifice type and comprises aneedle valve 66c which is adjustable relative to the orifice 66 to varythe effective size of the orifice and hence the restriction to flowtherethrough. The filter 67 can be of any suitable type and is hereinshown in the form of a generally conical screen that is removably seatedin a counterbore in the proportioner by a cap member 71.

It has been found that the syrup metering orifice tends to rapidlybecome clogged when syrup flows therethrough and that the provision of asyrup filter in advance of the syrup metering orifice is effective toreduce the rate at which the metering orifice becomes clogged but doesnot entirely stop clogging of the metering orifice and, moreover, itselfrapidly becomes clogged or loaded with material. This is believed to bedue to the small crystaline and gelatinous particles that are eitherpresent in the syrup due to improper mixing or which form in the syrupupon standing or when it passes through restricted passages such as thesyrup metering orifice. The partial clogging of the syrup meteringorifice and/or filter by gelatinous, crystaline or other foreignparticles in the syrup, changes the flow impedance in the syrup meteringline and hence changes the relative proportions of water and syrupsupplied to the mixed beverage delivery line 54. In accordance with thepresent invention, provision is made for cleaning the syrup meteringorifice and filter without requiring disassembly or removal of the samefrom the proportioning apparatus and further without adversely affectingthe syrup in the syrup delivery line or the mixed beverage in the mixedbeverage delivery line. More particularly, the syrup control valve 68 isarranged so as to effect back flushing of the syrup flow restrictor 66and syrup filter 67, utilizing water delivered under gas pressurethrough the water delivery line 51. The valve 68 includes a valve member68a which is normally biased by spring 69 to the position shown in FIGS.1 and 5 in which it communicates the syrup inlet 52a with the inlet 67bof the syrup filter 67. The valve is selectively and preferably manuallymovable under the control of a push button 68b to a second positionblocking flow of syrup from the syrup inlet and communicating the filterinlet 67b with a drain passage 73. When the valve member 68a is in itssecond position, water under gas pressure flows in the reverse directionthrough the syrup flow restrictor 66 and syrup filter 67 to the drainoutlet to back flush and clean the syrup flow restrictor and filter. Theback flushing and cleaning of the syrup flow restrictor and filter isthus achieved without requiring removal of the same from theproportioner or any change in the setting of the adjustable syrup flowrestrictor. Moreover, since the syrup inlet is shut off during backflushing, contamination of the syrup line is avoided. In addition, sincethe pressurized water supply to the proportioner 19 is also used toeffect back flushing, contamination of the mixed beverage delivery lineis also avoided. The back flushing rapidly carries away any deposits inthe syrup metering orifice or in filter and cleaning of the same can beeffected in very short time, of the order of a few seconds. Because ofthe speed and the ease with which cleaning of the syrup metering orificeand filter can be achieved, the operators of the beverage dispensingmachine can and normally will effect relatively frequent cleaning of thesame to assure accurate proportioning of the water and syrup in themixed beverage. To further facilitate the cleaning operation, theproportioning apparatus is preferably mounted as shown in FIG. 6 so thatthe push button actuator 68b is accessible from the front of themachine.

The water and syrup for producing the beverage mixture are mixed in theproportioner 19 and provision is advantageously made in the proportionerfor sampling the beverage mixture before it passes through the mixedbeverage delivery line to the freezing cylinder 21. In this manner, thebeverage mixture can be checked and adjusted if necessary to achieve thedesired proportions of water and syrup without having to drain orotherwise clear the entire freezing cylinder. As best shown in FIGS. 1and 4, a beverage sampling valve 81 of the on-off type has its inlet 82connected through a sample flow restrictor 83 to the mixing chamber 58to receive mixed beverage therefrom and has its outlet connected to asample delivery passage 84. The valve 81 is normally positioned by aspring 85 to block flow to the sample passage 84 and is movable underthe control of a manually operable actuator 81b to an open position topass a sample of the mixed beverage to the sample outlet passage 84. Thebeverage sample can then be analyzed to determine whether it has theproper syrup-water mixture and the syrup flow restrictor can then beadjusted, if necessary, in a direction to correct any error in themixture. The rate of flow of water and syrup through their respectiveflow restrictors will vary with the pressure drop across the flowrestrictors. Accordingly, the sample flow restrictor 83 is selected soas to produce a back pressure at the beverage mixing chamber 58, whenthe sample valve 81 is open, which pressure approximates the pressure inthe mixed beverage delivery line 54 when the delivery line valve 55 isopen.

The beverage dispensing apparatus and proportioning system isparticularly adapted for use in dispensing semi-frozen beverages. Thefreezing cylinder 21 is of conventional construction and includes afreezing chamber 91 that is refrigerated by the evaporator coil 92 of asecond refrigeration system including a compressor 93, condenser 94 andexpansion control valve 95. The second refrigeration system is cycled onand off under the control of a temperature sensor 162 to maintain atemperature in the freezing chamber which is somewhat below normal waterfreezing temperature and sufficient to form ice and, for example, of theorder of 25°-28° F. A defrost valve 98 is preferably provided in therefrigeration system and connected to pass hot gas from the compressor93 through a by-pass line 99 to the inlet end of the evaporator coil 92to effect rapid defrosting of the freezing cylinder when valve 98 isopened.

The freezing cylinder has a scraper and beater 101 mounted therein anddriven as by a speed reducer 102 and drive motor 103. As isconventional, the beater 101 includes scraper blades 101a for removingfrozen product from the chamber walls and agitator blades 101b forstirring and agitating the product in the freezing cylinder. A productdispensing valve 104 is connected to the forward end of the cylinderadjacent the cylinder end and is movable from a normally closed positionto an open position to dispense semi-frozen product from the freezingchamber. Mixed beverage is supplied to the freezing chamber through afreezing chamber inlet 105 preferably located adjacent the top of thefreezing chamber and at the end remote from the dispensing valve 104. Afloat chamber 106 communicates with the freezing chamber inlet 105 andis connected to the mixed beverage delivery line 54 to receive mixedbeverage when the solenoid valve is opened. The float chamber 106extends above the freezing chamber and has a means, such as a float 107in the chamber and a float operated switch 108 for sensing the liquidlevel in the float chamber to determine when the freezing chamber isfull of liquid. The beverage feed and proportioning apparatus can beutilized to deliver mixed beverage at atmospheric pressure to a freezingchamber having an atmospherically vented float chamber and with thedelivery valve 55 controlled by the float operated switch 108 to openand close as required to maintain the freezing chamber filled. However,the carbon dioxide gas in the mixed beverage tends to escape atatmospheric pressure. In order to improve the amount of overrun and theconsistency of the product, the mixed beverage is preferably deliveredto the freezing chamber under a preselected pressure somewhat below thegas pressure maintained on the water and syrup storage vessels. In thepreferred embodiment illustrated, the float chamber 106 is closed orsealed and an improved system is provided for delivering mixed beverageunder pressure to the freezing chamber to maintain the pressure andliquid level in the chamber generally uniform. As diagrammatically shownin FIG. 1, a gas bleed valve 111 is connected through a line 112 to thefloat chamber above the liquid level therein. In addition, a pressureswitch 113 is connected to sense the pressure in the float chamber andhence the pressure in the freezing chamber. The beverage delivery valve55 and gas bleed valve 111 are operated under the control of the liquidlevel sensing switch 108 and pressure switch 113 to admit mixed beverageto the freezing chamber and bleed gas from the freezing chamber untilthe liquid reaches a preselected level and pressure in the freezingchamber.

Reference is now made more specifically to the schematic diagram of theelectrical control circuit in FIG. 2. The main power supply conductors121 are adapted for connection to a power supply source through circuitbreakers 123. The motor 33a that drives the compressor 33 for thecarbonator, is connected to the main power conductors 121 and 122through an overload relay 124, start relay 125 and temperature controlswitch 126 operated by a temperature sensor 126a (FIG. 1) which sensesthe temperature in the carbonator. The sensor 126a is arranged tooperate switch 126 to a closed position when the temperature in thecarbonator rises above a preselected maximum, to thereby start thecompressor motor and refrigerate the carbonator, and to open the switch126 when the temperature drops to a preselected minimum to stoprefrigeration of the carbonator and thereby maintain the temperature ofthe liquid in the carbonator between preselected limits, for examplearound 34°-36° F. The condenser fan motor 34a for the condenser 34 isconnected so as to be started when the switch 126 is closed.

The drive motor 93a for the freezing chamber refrigeration compressor 93and the condenser cooling fan motor 94a for the condenser 94 areconnected to the main power conductors 121 and 122 through a start relay131 operated by a relay coil 131a. The beater drive motor 103 isconnected to the main power conductor 122 and through a conductor 132and manually operable switch 133 to the other main power conductor 121to start the beater motor whenever the switch 123 is moved intoengagement with either contacts 133a or 133b. The beater motor 103 willtherefore drive the beater continuously whenever the switch 133 is movedto a position into engagement with contact 133a and the refrigerationapparatus for the freezing cylinder is preferably operated under thecontrol of a switch 135 operated by a mechanism 135a (FIG. 1) whichsenses the freezing condition in the freezing chamber. The mechanism135a is conveniently of the type shown in the U.S. Pat. to Harker No.3,298,190 issued Jan. 17, 1967 and which is arranged to sense theviscosity or stiffness of the semi-frozen product in the freezingchamber and to start and stop the refrigeration apparatus to maintainthe product at a preselected consistency. The consistency sensing switch135 is normally closed and is opened only when the consistency of theproduct increases above a preselected maximum. As shown in FIG. 2, arelay coil 136 is connected to one of the power conductors 122 andthrough conductor 137 and normally closed viscosity switch 135 to aconductor 138. Conductor 138 is connected to contact 134a of a manuallyoperated switch 134 and switch 134 is connected through conductors 139and 140 to a contact 62a of the syrup sensing switch 62. Syrup sensingswitch 62 is herein shown of the two-position type which is arranged toengage contact 62b in the absence of syrup in the syrup delivery lineand to complete a circuit to an indicator lamp 141. When syrup ispresent in the delivery line, switch 62 is moved into engagement withcontact 62a and switch 62 is connected through conductor 143 to acontact 144b of a manually operable fill switch 144. The fill switch 144is manually operable and, during normal operation of the beveragedispenser, is moved to a "fill" position engaging contact 144b. Switch144 is otherwise connected through conductor 145 to the power conductor121 to thereby complete a circuit through relay coil 136 when the fillswitch 144 is in its fill position engaging contact 144b and when theswitch 134 is in its "automatic" position engaging contat 134a and thesyrup sensing switch 67 senses the presence of syrup in syrup deliveryline and engages contact 62a. When coil 136 is energized, it closesrelay contacts 146a and 146b and completes a circuit from conductor 122through the compressor motor start relay 131a, conductor 147, contacts146b, 146a, and conductor 148 to main power conductor 121 to start thecompressor drive motor. Operation of the refrigeration system will thenbe under the control of the viscosity sensing switch 135 which startsand stops the compressor to maintain a preselected product viscosity.When starting up the system, the syrup line is sometimes filled with airor gas and the syrup sensing switch will remain in engagement withcontact 62b. In order to start the system under these circumstances,switch 144 is manually movable into momentary engagement with contact144a. This completes a circuit from conductor 139 to the main powerconductor 121 and by-passes the syrup sensing motor.

The product pressure switch 113 is connected through conductor 151,conductor 140, syrup sensing switch 62, condenser 143 and fill switch144 to the main power conductor 121 to complete a circuit to thesolenoid 55a for the delivery valve to open the same under the controlof the pressure switch 113. As shown in FIG. 2, product pressure switch113 is of the twoposition type and is normally positioned in engagementwith contacts 113a when the pressure is below a preselected value tocomplete a circuit to the solenoid 55a for the delivery valve 55 to openthe same. This will allow fluid to flow through the delivery line to thefloat chamber 106 and freezing chamber 91. The pressure operated switch113 will thus open and close contacts 113a to open and close thedelivery line valve 55 as required to maintain the product in thefreezing chamber within a preselected pressure range below the gaspressure maintained on the water and syrup supply sources. For example,if the gas pressure regulator 42 for the pressurizing gas from the tank17 is set to maintain a pressure of about 30 p.s.i. in the water andsyrup storage vessels, then the pressure switch 113 is set to operate ata somewhat lower pressure, for example 20 p.s.i. and to close contacts115a when the pressure drops to a minimum value for example 18 p.s.i.and open contacts 113 when the pressure rises to an upper value such as20 p.s.i.

Provision is made for automatically bleeding any excess gas from thefreezing chamber to maintain the same filled with product. As shown inFIG. 7, contact 113b of the pressure switch 113 is connected throughconductor 155 to the level sensing switch 108 and the level sensingswitch is connected to the electro-responsive operator or solenoid 111afor the bleed valve 111. As will be seen, the pressure switch 113 willestablish a circuit through contact 113b to the level switch 108 onlywhen the pressure in the freezing chamber is above the minimum of 20p.s.i. and, if the liquid level is below the desired level, the switch108 is closed to open the bleed valve and bleed off gas from thefreezing chamber. This reduces the pressure in the freezing chamber sothat the pressure switch 113 will move back into engagement with contact113a and again open delivery valve 55. A gas indicator lamp 109 operatedunder the control of a pressure switch 110 in the gas line 43 isadvantageously provided to indicate when the gas tank 17 is out of gas.

The control circuit also includes a defrost circuit for operating thedefrost valve 98 in the freezing cylinder refrigeration system. Adefrost temperature sensor 161 mounted to sense the temperature of thefreezing cylinder preferably adjacent the delivery end and is arrangedto operate a switch 162. A defrost relay 163 includes a defrost relaycoil 164 and first and second relay operated switches 165 and 166. Thedefrost relay coil 164, the solenoid 98a for operating the defrost valve98 and an indicator light 168 are connected in parallel from conductor122 and through conductor 171 to a normally open manually operabledefrost switch 172. The defrost switch 172 is operative, when closed, tocomplete a circuit to the other main power conductor 121 and therebyenergize the defrost solenoid 98a and to also energize the defrost relaycoil 164. The normally open switch 162 operated by the defrosttemperature sensor is connected through conductor 174 to the main powerconductor 121 and is connected through conductor 173 to the relay switch165. Thus, if the defrost temperature sensor senses that the temperaturein the freezing chamber is below a selected value, it will close switch162 and, when the defrost relay 164 is operated in response to closingof the manually operable defrost switch 172, switch 165 will establish aholding circuit to maintain the defrost solenoid 98 and defrost relay164 energized. Relay switch 166 is connected through conductor 178 toconductor 138 and relay contact 166a is connected through conductor 179to conductor 137. This establishes a circuit in parallel to theviscosity sensing switch 135 to energize the control relay coil 136 ifthe switch 135 is open and maintain the refrigeration compressorenergized during defrost of the system.

The liquid level sensing means 31 for maintaining a preselected liquidlevel in the water supply vessel can be of any suitable construction foroperating water control valve 24 to maintain the liquid level in thevessel. In the embodiment shown, the level sensor is of the dual-probetype having probes 31a and 31b. The electro-responsive actuator 24a forthe water control valve 24 is connected through normally closed relaycontacts 181a to the main power conductors 121 and 122. The probes areenergized from the secondary 182a of a transformer 182 connected to thepower supply. One side of the secondary of the transformer is connectedthrough a conductor 184 to the electrically conductive vessel 15 and theother side of the secondary is connected through a relay coil 181 andconductor 185 to one of the probes 31a. The relay coil 181 is alsoconnected through normally open relay contacts 181b and conductor 186 tothe other of the probes 31b. When the liquid in the receptacle reachesthe upper probe 81a, it completes a circuit between conductor 184 andconductor 185 to energize the relay coil 181. This opens the normallyclosed contacts 181a to deenergize the solenoid 24a and close the watercontrol valve 24. Energization of coil 181 also closes the normally opencontacts 181b to establish a circuit to the lower probe 31b. The coil181 will therefore remain energized until the liquid drops below theprobe 31b. At that time, relay coil 181 is deenergized and allowsnormally open contacts 181a to close and reenergize the water controlvalve to its open position.

A modified circuit for operating the bleed valve solenoid 111a anddelivery valve solenoid 55a as illustrated in FIG. 7 and like numeralsfollowed by the postscript .sup.(1) are used to designate thecorresponding parts. In the previous embodiment, the level sensingswitch 108 was connected in series only with the bleed solenoid 111a tooperate the bleed solenoid to its open position when the pressure wasabove a preselected value and the liquid level below a preselectedvalue. In the modified circuit shown in FIG. 7, the liquid level sensingswitch 108' is connected in series with both the bleed valve solenoid111a' and the fill valve solenoid 55a', to also prevent opening of thedelivery valve in the event the liquid level is above a preselectedvalue. More particularly, as shown in FIG. 7, the pressure switch 113'is connected to conductor 151 and contacts 113a' and 113b' arerespectively connected to the delivery valve solenoid 55a' and the bleedsolenoid 111a'. Both the fill solenoid and bleed solenoid are otherwiseconnected in series with the normally open liquid level sensing switch108' to main power conductor 122. With this arrangement, the floatchamber cannot be overfilled even if there is a loss of gas pressure dueto a leak or the like, since the liquid level sensing switch 108 willalso prevent the opening of the delivery valve when the liquid is abovea preselected level. This allows some room for the semi-frozen productin the freezing chamber to expand and thus prevents build-up ofexcessive pressure in the freezing chamber due to expansion of thebeverage as it freezes.

From the foregoing it is thought that the construction and operation ofthe beverage dispensing system will be readily understood. The water andflavoring syrup are separately stored in vessels 15 and 16 under thesame substantially constant gas pressure, for example about 30 p.s.i.and are delivered under this gas pressure through the water and syrupdelivery lines 51 and 52 to the proportioner 19. The water and syrupwill flow through their respective flow restrictors 57 and 62 to themixed beverage delivery line when the delivery valve 55 is open at ratescontrolled by relative impedances of the flow restrictors 57 and 66. Asample of the mixed beverage can be obtained before passage to thefreezing chamber by operating the sample valve 81 to its open position.As previously described, the sample flow restrictor 83 is adjusted tomaintain a back pressure in the system correlative with the pressure inthe delivery line when the valve 55 is open to assure that thecomposition of the sample is substantially the same as will be suppliedto the delivery line. If the composition of the sample is in error, theproportions can be adjusted by adjusting the flow restrictor 66 and anew sample taken again before introduction into the freezing chamber. Inthis manner, the effect of changes of the flow restrictors on the samplecomposition can be quickly determined and without requiring draining orremoval of the material from the freezing chamber.

The syrup flow restrictor 66 and syrup filter 67 will become cloggedmore or less frequently during dispensing. They can be readily cleanedin place by manually operating the back flush valve 68 to shut off theflow of syrup while venting the filter inlet to drain to cause the waterunder gas pressure to flow in the reverse direction through the syrupflow restrictor and filter.

During normal operation of the beverage dispenser, switch 133 ismanually positioned in engagement with contact 133a; switch 134 inengagement with contact 134a and switch 144 in engagement with contact144b. The control circuit will then operate the delivery valve 55 underthe control of the product pressure sensing switch 113 to maintain thepressure in the freezing chamber and hence the back pressure on theproportioner at a preselected value such as 20 p.s.i. which issubstantially below the gas pressure on the water and syrup in thevessels 15 and 16. The gas bleed valve 111 is automatically operatedunder the control of the liquid level sensing switch to bleed off anyexcess gas to maintain the freezing chamber filled. The refrigerationcompressor 93 is operated under the control of the viscosity sensingswitch 135 to maintain a preselected product viscosity.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An apparatus fordispensing beverages containing water, a flavoring syrup and food-gradegas comprising, a mixed beverage delivery line having delivery valvemeans movable between an open and a closed position for controlling flowof mixed beverage therethrough, water storage means for storing aquantity of water and having a water feed line, syrup storage means forstoring a quantity of flavoring syrup and having a syrup feed line,water flow restricting means connecting said water feed line to saidbeverage delivery line, a syrup filter having a filter inlet and afilter outlet and a syrup flow restricting means connecting the filteroutlet to said beverage delivery line, a syrup control valve meanshaving a first connection to said syrup feed line; and a secondconnection to said filter inlet and a drain connection, said syrupcontrol valve means including means selectively movable from a normalposition communicating said first connection with said second connectionwhile blocking flow through the drain connection and a back flushposition blocking flow through the first connection while communicatingthe second connection with the drain connection, gas pressurizing meansincluding a source of food-grade gas for supplying gas under apreselected substantial constant pressure to said gas inlet of saidwater storage means to feed water under the gas pressure through thewater feed line and water flow restricting means to the beveragedelivery line, said gas pressurizing means including means for supplyinggas under substantially the same preselected pressure to said gas inletof said syrup storage means to feed syrup under the gas pressure throughthe syrup feed line and in one direction through the filter and syrupflow restricting means to the beverage delivery line when said syrupcontrol valve is in its normal position, said syrup control valve beingoperative in its back flush position to block the flow of syrup from thesyrup feed line and to communicate the filter inlet with the drainconnection whereby water under the gas pressure from the water feed linewill flow in the other direction through the syrup flow restrictingmeans and syrup filter to drain to back flush the same.
 2. An apparatusfor dispensing beverages according to claim 1 wherein at least one offlow restricting means is adjustable to relatively vary the rates offlow of syrup and water through the respective syrup and water flowrestricting means under said preselected gas pressure.
 3. An apparatusfor dispensing beverages according to claim 1 wherein said syrup flowrestricting means is adjustable to vary the rate of flow of syruprelative to the rate of flow of water when the delivery line valve isopen.
 4. An apparatus for dispensing beverages according to claim 1including a normally closed sample valve connected to said delivery lineand selectively movable to an open position to pass a sample of mixedbeverage therefrom, and sample flow restricting means for restrictingthe rate of flow through the sample valve when the sample valve is opento maintain a substantial pressure in the delivery line.
 5. An apparatusfor dispensing semi-frozen beverages containing water, flavoring syrupand a food-grade gas comprising, a freezing chamber having a rotarybeater therein for freezing a semi-frozen beverage, a dispensing valveconnected to the freezing chamber for dispensing beverage therefrom,beverage delivery means including a mixed beverage delivery line forconveying mixed beverage to the freezing chamber, water storage meansfor storing a quantity of water and having a gas inlet and water feedline, syrup storage means for storing a quantity of flavoring syrup andhaving a gas inlet and a syrup feed line, water flow restricting meansconnecting the water feed line to said beverage delivery line, a syrupfilter having a filter inlet and a filter outlet and a syrup flowrestricting means connecting the outlet of the syrup filter to saidbeverage delivery line, a syrup control valve means having a firstconnection to the syrup feed line and a second connection to the filterinlet and a drain connection, said syrup control valve means includingmeans selectively movable from a normal position communicating saidfirst connection with said second connection while blocking flow throughthe drain connection and back flush position blocking flow through thefirst connection while communicating the second connection with thedrain connection, gas pressurizing means including a source offood-grade gas for supplying gas under a preselected substantiallyconstant pressure to said gas inlet of said water storage means to feedwater under the gas pressure through the water feed line and water flowrestricting means to the beverage delivery line, said gas pressurizingmeans including means for supplying gas under substantially the samepreselected pressure to said gas inlet of said syrup storage means tofeed syrup under the gas pressure through the syrup feed line and in onedirection through the filter and flow restricting means to the beveragedelivery line when said syrup control valve is in its normal position,said syrup control valve being operative in its back flush position toblock the flow of the syrup from a syrup feed line and to communicatethe filter inlet with the drain connection whereby water under the gaspressure from the water feed line will flow in the other directionthrough the syrup flow restricting means and syrup filter to drain toback flush the same.
 6. An apparatus for dispensing semi-frozenbeverages according to claim 5 wherein at least one of the flowrestricting means is adjustable to relatively vary the rates of flow ofsyrup and water through the respective syrup and water flow restrictingmeans under said preselected gas pressure.
 7. An apparatus fordispensing semi-frozen beverages according to claim 5 wherein saidsource of food-grade gas comprises a tank of carbon dioxide gas, andsaid water storage means includes means for carbonating the watertherein.
 8. An apparatus for dispensing semi-frozen beverages accordingto claim 5 including a delivery valve in the delivery line movablebetween an open and a closed position for controlling flow of mixedbeverage to the freezing chamber, and delivery valve control means foroperating said delivery valve to maintain freezing chamber filled to apreselected level.
 9. An apparatus for dispensing semi-frozen beveragesaccording to claim 8 wherein said delivery valve control means includesmeans for closing said delivery valve when the pressure in the freezingchamber reaches a value substantially below said preselected gaspressure.
 10. An apparatus for dispensing semi-frozen beveragesaccording to claim 8 including a sample valve communicating with saiddelivery line ahead of the delivery valve and selectively movable from anormally closed position to an open position to allow sampling of themixed beverage before it enters the freezing chamber.
 11. An apparatusfor dispensing semi-frozen beverages according to claim 5 including adelivery valve in the delivery line movable between an open position anda closed position for controlling flow of mixed beverage to the freezingchamber, delivery valve operating means responsive to the pressure inthe freezing chamber for closing the delivery valve when the pressure inthe freezing chamber reaches a pre-set upper pressure substantiallybelow said preselected gas pressure and for opening the delivery linevalve to allow flow of mixed beverages to the freezing chamber when thepressure drops to a pre-set lower pressure below said pre-set upperpressure.
 12. An apparatus for dispensing semi-frozen beveragesaccording to claim 11 including a sample valve communicating with thedelivery line ahead of the delivery valve and movable from a normallyclosed position to an open position to allow sampling of the mixedbeverage before it enters the freezing chamber.
 13. An apparatus fordispensing semi-frozen beverages according to claim 12 including sampleflow restricting means for restricting the flow through the sample valvewhen the latter is open to maintain the pressure in the delivery linesubstantially above atmospheric pressure.
 14. An apparatus fordispensing semi-frozen beverages according to claim 5 wherein saidbeverage delivery means is operative to deliver the mixed beverage underpressure to the freezing chamber and includes a delivery valve in thedelivery line movable between an open and a closed position forcontrolling flow of mixed beverage to the freezing chamber, a gas bleedvalve movable between a closed and an open position and connected tobleed gas from the freezing chamber, liquid level means for sensing theliquid level in the chamber, pressure sensing means for sensing thefluid pressure on the beverage in freezing chamber, and control meansresponsive to said liquid level sensing means and said pressure sensingmeans for operating said delivery valve and said bleed valve to admitmixed beverage to the freezing chamber and bleed gas from the chamberuntil the liquid reaches a selected level and pressure in the freezingchamber.
 15. An apparatus for dispensing semi-frozen beverages accordingto claim 14 wherein said control means is operative to close said bleedvalve when the delivery valve is open.
 16. An apparatus for dispensingsemi-frozen beverages according to claim 5 wherein said beveragedelivery means is operative to deliver the mixed beverage under pressureto the freezing chamber and includes a delivery valve in the deliveryline movable between an open and a closed position for controlling flowof mixed beverage to the freezing chamber, delivery valve operatingmeans responsive to the pressure in said freezing chamber for closingthe delivery valve when the pressure in a freezing chamber reaches apre-set upper pressure substantially below said preselected gas pressureand for opening the delivery line valve to allow flow of mixed beverageto the freezing chamber when the pressure drops below said pre-setpressure, a gas bleed valve connected to bleed gas from the freezingchamber, liquid level sensing means for sensing the presence of excessgas in the freezing chamber, gas bleed valve operating means responsiveto said liquid level sensing means for operating said gas bleed valve toits open position when excess gas is present in the freezing chamber.17. An apparatus for dispensing semi-frozen beverages containing water,flavoring syrup and a food-grade gas comprising, a freezing chamberhaving a rotary beater therein for freezing a semi-frozen beverage, adispensing valve connected to the freezing chamber for dispensingbeverage therefrom, beverage delivery means including a mixed beveragedelivery line for delivering mixed beverage under pressure to thefreezing chamber, a delivery valve in the delivery line movable betweenan open and a closed position for controlling flow of mixed beverage tothe freezing chamber, a gas bleed valve movable between an open and aclosed position and connected to bleed gas from the freezing chamber,liquid level sensing means for sensing the liquid level in the chamber,pressure sensing means for sensing the pressure on the beverage in thefreezing chamber, and control means responsive to said liquid levelsensing means and said pressure sensing means for operating saiddelivery valve and said bleed valve to admit mixed beverage to thefreezing chamber and bleed gas from the chamber until the liquid reachesa preselected level and pressure in the freezing chamber.
 18. Anapparatus for dispensing semi-frozen beverages according to claim 17wherein said control means is operative to close said bleed valve whenthe delivery valve is open and close said delivery valve when the bleedvalve is open.
 19. An apparatus for dispensing semi-frozen beveragesaccording to claim 18 wherein said liquid level sensing means includesan enclosed beverage chamber external to said freezing chamber andconnected to said delivery line and to said freezing chamber, and meansfor sensing the liquid level in the beverage chamber.
 20. An apparatusfor dispensing semi-frozen beverages according to claim 17 wherein saidliquid level sensing means includes an enclosed beverage chamberexternal to said freezing chamber and connected to said delivery lineand to said freezing chamber, and means for sensing the liquid level inthe beverage chamber.